With Don Mattrick Out, Who Will Manage Microsoft's Xbox?

Microsoft Corp.'s Xbox division was already in crunchtime before losing its leader to Zynga Inc. Now it faces a new question: Who will take over the videogame business?

Under the leadership of Don Mattrick, Microsoft this spring unveiled a new console that is crucial to its longtime rivalry with Sony Corp. and Nintendo Co. as well as the software company's broader ambitions to deliver entertainment in the living room. But the Canadian videogame veteran, in a move announced Monday, chose to take on turnaround chores as...